DYNAMIC RESPONSES AND RELIABILITY ANALYSIS OF STOCHASTIC STRUCTURES UNDER MAIN SHOCK-AFTERSHOCK SEISMIC SEQUENCES

摘要

Strong aftershocks may lead to the damage of structure even when it performs well in the main shock.However,the responses of structures under main shock-aftershock seismic sequences remain unclear.Dynamic responses and reliability of an existing reinforced concrete(RC)frame subjected to main shock-aftershock seismic sequences are analysed in this paper.Consideration is given to the randomness that comes from both structures and excitations.The probability density evolution method(PDEM)and two methods of reliability assessment are used in this study.Comparison of methods shows that the results agree well with the Monte Carlo simulation(MCS).Compared to results for structures subject to main shock only,strong aftershock results showed a greatly enlarged dynamic response of the structure,which significantly reduced seismic reliability.The decreased extent of reliability depends on nonlinearity level of structures under main shock.Because of damage accumulation in main shock,the damaging effects of strong aftershocks can't be ignored,which must be considered in the seismic design and reliability analysis of structures.Furthermore,due to its lower computational cost,the PDEM can be used in dynamic responses and reliability analysis of stochastic structures with advantages of high efficiency and accuracy.